Tachometer.



'110.728,529.' PATENTBD MAY1'9,190J3.5

.W. P. WIBMANN.

TAGHOMETER. APPLICATION FILED JAN'. 28. 1902.

'No MODEL.

WITNESSES UNITED STATES,

Patented May 19, 1963.

r PATENT OFFICE.

WILLIAM P. WIEMANN, OF WASHINGTON, PENNSYLVANIA.

TCHOMETER.

SPECIFICATION forming part of Letters Patent No. 728,529, dated May 19, 1903. Application ledrJanuary 2k3, 1902. Serial No. 91,6015.y (No modeld To all whom, it may concern: l A

Be it known that I, WILLIAM P. WIEMANN, of Washington, in the county of Washington and State of Pennsylvania, haveinvented a new and useful Tachometer, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification,

Y in whichcaused by this fan acting'upon a vane-indi.

cator, which is thus movedto different points on the dial under the varying pressure caused` bythe different speeds; and the invention is4 designed to simplify and improve such devices and make them portable, convenient, and practical.

In the drawings, 2 representsa metallicV case, having a base Sand a removable top crystal 4 with a dial or scale marked around its edge. The graduations of the dial are spaced successively a greater distance apart,

starting at the zero-point, and 4I have found by experiment that this is necessary in order to obtain accurate results on account of the successively-easier movements of the needle and reduced resistance of the spring. The driving-spindle 5 extends across the case from side to side in a horizontal direction, is provided with a clutch-socket 5 at each end, andY carries a miter-gear 6, intermeshing with a similar ruiter-gear 7, mounted'on a stub-shaft 8, projecting vertically within the bottom ot' the case. A spur gear-wheel 9 is secured to or formed integrally with the miter-gear 7 and intermeshes with a pinion 10, secured toI a counter-shaft 11, tothe upper end of which? is secured a spur-gear l2. The spur gearwlleel12 intermeshes witha centrally-located pinion 13, having secured thereto a disk 14V carrying fan-blades 15. The pinion 13, which carries the fan-wheel, rotates around the stern' and below the head of a fiat-head screw 15, in which is centrally secured a stationary vertical pin 17. A needle 18, which is in the form of a vane with depending end portions soldered or secured, tor a sleeve 19. screw 20 is screwed into the upper end of the rection of movement of the vane.

18 beyond and spanning the fan-blades, is

sleeve 19, the lower tapered end of this screw being polished and resting upon the upper polished fiat end o'f .pin 17. The screw 20 vprojects above the sleeve, which is provided with a flange supporting an inertia-disk 21. The disk has a central hole which the screw enters, allowing it to rest upon the liange, upon which it is free to rotate, givinga braking action.

`To form a yielding resistance for the pointer-vane, against which resistance the air-currents act, Iprovide thespiral spring 22, having a hub123, which is forced down over the 'stationary pin17. The outer or free end of the spring isheld by a sealing-wax clamp 24 atlthe lower end of theY stem 25, secured to the pointer-vane.` The vane-or pointer is brought Vto zero by turning the spring-hub laround onrits carrying-pin, the strength of thev spring being changed by unsealing and moving the spring to a new position and resealing. f y Y The gearing is arranged so that the drivingspindle 5 is parallel to the dial, and this gearing also provides for giving a high rotative speed to the fan, both of these features being important to a practical and portable device.

A short The disk 14 of the fan is provided with vent or circulating holes 26 near` the center to allow air to be drawn from below to the pointl from which the air is'takcn by the fan. The use of twoconnections at opposite ends of to shafts turning in clockwise or counterclockwise direction without changing the di- I thus prevent a reverse tension of the spring which would cause the spring, to lose its adjustment.

In the operation of the device a center stem 5 is connected directly to the center of shaft to be tested, and the fan is thus driven at a 4high speed. The air which is drawnthrough the holes in the fan-disk to the vane side is the case. The vane which has been held in the shaft 5 enables thedevice to be applied IOC proper normal position by the spring is thus deflected by the air-current from its normal position to some position at an angle thereto dependent upon the speed of rotation of the fan. The inertia-brake 21 is not affected by the air-currents, but acts as a resistance to the start or stop of the vane upon which this disk rests and prevents an unsteady or hunting action of the indicator-vane, which would come to a point of unsteady balance between the force of the spring and that of the aircurrents. This unsteadiness is prevented by the action of the inertiadisk, which is light in Weight but of large diameter. The disk is not acted on by air or the spring-ring, but moves freely with vane in either direction. Its sole function is to retard sudden starts or stops of the vane. When both vane and disk are in motion, a sudden stop of the vane is prevented by the disk. The friction between the disk and the flange on which it rests tends to prevent motion between both.

If force is applied to the vane sufficient to cause a quick movement thereof, the disk will not move until the vane has started, the disk gaining speed as the vane advances,thus retarding the progress of the vane, and later the disk aids the vane and prevents a sudden start back when released by the force which causes the' swing. If the vane should tend to stop suddenly, the disk continues and the friction between the disk and the vane prevents a sudden stop and a backward swing, which would occur without the use of the bl'akedisk. The momentum which is set up in the disk by movement of the vane as a result of the friction between the two retards the start of the vane, and if the power applied to the vane is insufficient to set up the momentum in the disk no movement of the vane will result. 'Ihus the unsteadiness of vane caused by balancing between the force of the air-currents and spring are prevented by the disk.

The advantages of the invention result from the use of the speeding-up gearing,

which raises the rotating speed of the fan above that of shaft being tested to such a point that a practical instrument is thus obtained. Without this the speed of the fanwheel would not be sufcient for a device of ordinary size. The action of the balancedisk is of peculiar advantage, as also the bevel-gear arrangement and the general compact arrangement of the parts. The changing spacing of the graduations gives correct readings. The supporting of the needle-vane at the top gives a very sensitive adjustment and a much better action than Where it is fixed to a shaft having two hearings, and the means for attaching to either end of the shaft 5 makes the device economical.

Many variations may be made in the form and arrangements of the parts without departing from my invention.

I claiml. A speed-indicator or tachometer having a rotary fan-wheel with inlet-openings therethrough, mechanism for rotating the fauwheel,and a pointer-vane spanning the wheel and actuated by the currents therefrom; substantially as described.

2. In a speed-gage or tachometer, a fanwheel provided with a disk having circulating air-inlets therethrough, and mechanism for rotating the same; substantially as described.

3. A tachometer having a rotary fan-wheel, a vane or needle acted upon by the air-currents, and an inertia-brake disk for the vane or needle having its weight equally distributed around the axis of the needle; substantially as described. e

4E. A tachometer having a fan-wheel, an indicator-vane having an annular flange, and an inertia-brake disk surrounding the vaneshaft loosely and supported on the flange, to exert a braking friction on said flange; substantially as described.

5. A tachometer having a fan-wheel, astationary pin projecting upwardly above the fan-Wheel and an indicator-vane above and spanning the blades of the fan-wheel and supported at the top on the pin; substantially as described.

6. In a tachometer, a vane supported on a stationary pivot and having an adjustable clamp connection with the outer end of a spiral spring, and a rotatory fan-Wheel arranged to act upon the vane; substantially as described.

In testimony whereof I have hereunto set my hand.

WILLIAM P. WIEMAN N.

Vitnesses:

ERNEST T. HALL, GEO. L. Soo'r'r.

IOO 

